The present invention relates to a developer cylinder and drive gear arrangement used with a developer-replenishing device in a copier, facsimile apparatus, printer or similar electrophotographic image forming apparatus.
FIG. 1 shows a developer cylinder and drive gear arrangement used in the developer-replenishing device of a copier, facsimile apparatus, printer or similar electrophotographic image forming apparatus. This arrangement comprises a drive gear A, and a developer cylinder E driven by the drive gear A. The drive gear A has a gear shaft B at its center. The gear shaft B has a twisted triangular coupling hole C axially disposed on its one end. The developer cylinder E is fixedly mounted with a transmission gear F having a twisted, triangular coupling shaft D axially raised from its one end for coupling to the coupling hole C on the gear shaft B of the drive gear A. Because the developer cylinder E wears quickly with use, it must be replaced when starting to wear, and the transmission gear F should also be replaced. Because the triangular coupling shaft D of the transmission gear F twists in one direction, its fabrication is complicated, resulting in a high manufacturing cost.